The present invention relates, in general, to a lip-type shaft seal.
Lip-type shaft seals are used to tightly seal pressure compartments from one another, and find in particular application in rolling-contact bearings of water circulating pumps for internal combustion engines, with the shaft seal being disposed between two components moving relative to one another. The shaft seal should hereby assume the task to prevent a penetration of water, vapor or similar fluids, such as coolant, and thus is required to effectively seal against the bearing surfaces throughout the service life of the rolling-contact bearing. An example of a lip-type shaft seal is described in German Pat. No. DE 38 43 337 A1. The shaft seal includes a seal body which is received in fixed rotative engagement in a groove and has a radial sealing lip terminating in an axial sealing lip. The radial sealing lip has a sealing edge which is acted upon by a spring element for support against a rotating shaft component which extends in the direction of a symmetry axis of the shaft seal. The axial sealing lip substantially overlaps a contact surface of a centrifugal sleeve. The relative short length of the axial sealing lip in concert with the substantial axial overlap between the axial sealing lip and the contact surface causes an increased pressure force which is accompanied by an inadmissible overheating. In particular, when high speeds are involved, wear is substantial and may ultimately lead to a “burning” of the sealing lip in the support zone, so that the operativeness of the shaft seal is adversely affected.
It would therefore be desirable and advantageous to provide an improved lip-type shaft seal to obviate prior art shortcomings and to construct it in a way that the support zones between the sealing lips and the opposing contact surfaces of the component interacting with the shaft seal are independent on the temperature and the rotation speed of the component.